This project is a large-scale (N =1505), longitudinal (three assessments at six-month intervals) study of critical transitions (sixth to ninth grades) during adolescence (11 to 16 years old) in a school-based community sample. Thus, this study is a repeated-measures, within-subjects design. Adolescents, their parents, and their teachers complete questionnaires on a broad set of constructs that are relevant to the development of depression in adolescence. The primary aim of the study is to examine the role of spirituality as a protective factor against the development of depression in adolescence. In addition, personal agency beliefs are examined as a potential mediator of the relationship between spirituality and depression. A major goal of this study is to identify a mechanism by which adolescents are buffered against the development of depression. Accordingly, the long-term objective of this research is to develop innovative interventions aimed at preventing the onset of major depression during the critical period of adolescence.